In recent years, devices conforming to a system such as MPEG (Moving Picture Expert Group) for handling image information as digital signals, and taking advantage of redundancy peculiar to the image information with transmission and accumulation of high effective information as an object at that time to compress the image information by orthogonal transform such as discrete cosine transform or the like and motion compensation, or the like have are becoming more widespread in both information distribution such as broadcasting stations, and information reception in general homes.
Specifically, for example, there have become widespread encoding devices and decoding devices used at the time of receiving image information (bit stream) compressed by an encoding system such as MPEG, H.26x, or the like employing orthogonal transform such as discrete cosine transform, Karhunen-Loéve transform, or the like, and motion compensation, via a network medium such as satellite broadcasting, cable TV, the Internet, or the like, or at the time of processing the image information on a recording medium such as optical, magnetic disk, or flash memory.
For example, MPEG2 (ISO/IEC 13818-2) is defined as a general-purpose image encoding system, and is a standard encompassing both of interlaced scanning images and sequential-scanning images, and standard resolution images and high definition images, and has widely been employed now by broad range of applications for professional usage and for consumer usage. By employing the MPEG2 compression system, for example, code amount (bit rate) of 4 through 8 Mbps in the event of an interlaced scanning image of standard resolution having 720×480 pixels that are width×length, 18 through 22 Mbps in the event of an interlaced scanning image of high resolution having 1920×1088 pixels are allocated, whereby a high compression rate and excellent image quality can be realized.
With MPEG2, high image quality encoding adapted to broadcasting usage is the principal object, but lower code amount (bit rate) than the code amount of MPEG1, i.e., an coding system having a high compression rate is not handled. Personal digital assistants becoming widespread will most likely lead to increased needs for such an encoding system from now on, and in response to this, the MPEG4 encoding system has been standardized. With regard to an image encoding system, the specification thereof was confirmed as an international standard as ISO/IEC 14496-2 in December 1998.
Further, in recent years, standardization of a standard called H.264 (ITU-T Q6/16 VCEG) is being advanced with image encoding for television conference usage as an object. With H.264, it has been known that as compared to a conventional encoding system such as MPEG2 or MPEG4, though greater computation amount is required for encoding and decoding thereof, higher encoding efficiency is realized. Also, currently, as part of the activities regarding MPEG4, standardization for taking advantage of a function that is not supported by H.264 with this H.264 as base to realize higher encoding efficiency has been done as a Joint Model of Enhanced-Compression Video Coding.
With regard to an encoding system (JVT Codec) wherein standardization is performed being performed by the Joint Video Team, in order to improve encoding efficiency as compared to existing techniques such as MPEG2, MPEG4, and so forth, various improvements have been studied. For example, with discrete cosine transform, transform to integer transform coefficients is performed with a block of 4×4 pixels as an object. Also, with regard to motion compensation, a block size is variable, and more optimal motion compensation can be performed. However, basic algorithms for encoding are the same as with the existing techniques, such as MPEG2, MPEG4, or the like.
Incidentally, as for image contents an object for encoding such as described above, in addition to 2D image contents, there are stereoscopic vision image contents wherein stereoscopic vision is available.
In order to display a stereoscopic vision image, a dedicated device (hereafter, device for stereoscopic vision) is needed, and as for such a device for stereoscopic vision, for example, there is an IP (Integral Photography) stereoscopic image system developed by NHK (Japan Broadcasting Corporation).
The image data of a stereoscopic vision image is made up of multiple viewpoints of image data (image data of images shot from multiple viewpoints), the greater the number of viewpoints is, and also the wider the range of viewpoints is, a subject can be viewed from various directions, as if it were, a “television which can be looked into” can be realized.
Here, an example of the image data of a stereoscopic vision image, i.e., encoding and decoding methods of multiple viewpoints of image data is described in PTL 1.